Attorney General Jeff Sessions said Thursday he will recuse himself from any existing or future investigations related to President Donald Trump's 2016 presidential campaign amid an ever-growing chorus of demands for him to step aside.

Details emerged late Wednesday that Sessions had met with a Russian diplomat last year and he failed to disclose those meetings during his Senate confirmation process, adding to the concerns about his impartiality on any investigation into alleged ties between surrogates for Trump's campaign and Russians.

Earlier in the day, Schumer also raised the the prospect of reviving a decades-old independent counsel law.

"If the Justice Department drags its feet and refuses to appoint a special prosecutor or select someone with insufficient independence, there is another route. We will then urge (Senate Majority Leader Mitch McConnell) and (House Speaker Paul Ryan) to work with Democrats and create a new and improved version of the independent counsel law, which would give a three-judge panel the authority to appoint an independent counsel," Schumer said.

Here's a breakdown on what may happen next:

Recusal

Sessions said that after consulting with career officials at the Justice Department, he would remove himself from any investigation into Trump and Russia, and allow Boente to oversee any investigations or prosecutions in his place. Given that Boente was selected after Trump fired Sally Yates for refusing to enforce the travel ban, this decision could still face political opposition.

But the recusal move has plenty of historical precedent.

For instance, in 2013 Attorney General Eric Holder recused himself from involvement in a Justice Department investigation into a leak that led it to surreptitiously collect telephone records from the Associated Press. In that case, the FBI investigation was supervised by Deputy Attorney General James M. Cole.

Special Counsel

Despite Sessions' recusal decision, an open question remains as to whether Boente will ultimately appoint a "special prosecutor" in his place.

The attorney general's regulations provide for appointment of outside "special counsel" by the attorney general in certain circumstances. Three conditions must be met: the attorney general (or acting attorney general) must determine that "criminal investigation of a person or matter is warranted," and that investigation or prosecution by a local US attorney's office or division of the Justice Department "would present a conflict of interest for the department or other extraordinary circumstances," and that "it would be in the public interest to appoint an outside special counsel to assume responsibility for the matter."

In other words, the decision to appoint special counsel in this case will rest sole with Boente -- not Sessions.

And while lawmakers on Capitol Hill have no role in the appointment of any prosecutor, that didn't stop top Democratic leadership from putting pressure on Boente to appoint someone else.

"Given these facts, there is no choice but for Mr. Boente to appoint a special prosecutor," said Schumer in a statement. "While Mr. Boente doesn't have the long political ties to President Trump, he is still in the President's chain of command and could be fired at will by the President, who has already fired the first person in this position."

Aside from the special counsel regulations, the attorney general (or Boente in this case) also has the general statutory authority to hire an outside attorney to oversee a federal criminal investigation.

For example, in 2003, then-Deputy Attorney General James Comey (who is now the FBI director), in his capacity as acting attorney general (upon recusal of Attorney General John Ashcroft), named Patrick Fitzgerald special counsel to investigate who leaked the name of CIA operative Valerie Plame Wilson amid mounting public pressure for an independent examination of the allegations. The investigation led to the conviction of Vice President Dick Cheney's then-chief of staff, Lewis "Scooter" Libby, for lying to a grand jury and obstruction of justice.

Sessions himself has not shied away from calls for special prosecutors. During the 2016 campaign, Sessions called on then-Attorney General Loretta Lynch to recuse herself from the investigation into Hillary Clinton's use of a private email server and to appoint a special prosecutor in the case.

Independent Counsel Act

Prior to the regulations regarding special counsels, Congress passed the Ethics in Government Act of 1978 after Watergate, which provided for the appointment of "independent counsels."

Under that law, the attorney general would petition a special three-judge panel to name an independent counsel after receiving credible allegations of criminal misconduct by a federal employe whose prosecution might give rise to an appearance of a conflict of interest.

Yet the law was widely criticized by many after Kenneth Starr's lengthy investigation into President Bill Clinton, and in 1999, Congress allowed the independent counsel provisions of the law to lapse.

"The law was not drafted tightly enough. But in this case, cognizant and wary of that history, we would work to craft a narrow authority, with specific guidelines for this investigation, to prevent this from becoming a political witch hunt," Schumer said Thursday.

While in theory it is possible that Congress could reauthorize the independent counsel law as Schumer suggests, it would not necessarily be smooth sailing given that Republicans control the Senate and he would need bipartisan support for any new measure.